Method of scanning and apparatus therefor



SUBSTITUTE FOR MISSI M y 28, 1935. I o. A. ROSS 2,002,578

' I METHOD OF SCANNING AND -APPARATUS THEREFOR Filed Dec. 9, 1930 nnnnnnunuououou\ mammal i i I i 1 Patented May 28, 1935 t This invention refers to television broadcast ing and more particular to that phase of television broadcasting wherein the picture to be transmitted is scanned by abeam of light. In the broadcasting of television motion pic-' three a, present=method .of scanningsthe film comprises in directing a beam of'light' onto a vibrating =mirrorp' arranged to project there fiected .beam onto the'film in a sinusoidal path, the beam'moving constantly from Ioneside'of the film to the other asthe film is: advanced. If the beam is made sufficiently narrow, and the film is moved sufliciently fast to prevent superimposed scanning as the film "advances. acomparatively large area of the picture remains unscanned whereas if the beam is made sufiiciently wide, and thefilm is advanced sufliciently slow to scan the entire area of the pictures, a' comparatively large portion of the area, more especially at the edges of the pictures is. double scanned with the result that the picture as viewed at the television receiver is distorted in that portion wherein superimposedscanning occurs. Another method of'scanning'also producing distortionconsists in employing a scanning disk of known form having spirally'located apertures arranged to successively expose difiering portions of an attenuated fixed light beam: more-fully hereinafter described. .ywzscr 'v 1M. -It is the prime object'of the invention to overcome the difficulty ofsuperimposed scanning by providing a system, or method wherein the pictures areunidirectionally scanned and wherein the scanning light beam is moved continually in one direction across the picture, Jthebeams being so closely approximated that substantially the-entire area of-the pictures are scanned without superimposition of the scanning spot, on any portion thereof. 1': e Another object is to furnish novel apparatus for efiecting the aforesaid unidirectional scanning of televised motion pictures. :;.i; 1.1";" Another object is to furnish novel.scanning apparatus whereina' scanning spot. is continuously moved at a uniform rate of ,travelacross a sc n bj -1 "4 2*": "1 i: a"? 1 Another object isto furnish novelly formed 1 light beams for scanning televised motion picturessj '2' =3f5f'3fj2'1rfi'i Itv: iiflwsffp Qther"ob ect s and advantagesvwillappear as: the description of the invention progresses, and; the novel feature of the inventionwill be pointed out in the appended claims. This'inv ention'consists in the novel construce; tion and arrangement of partsflhereinafter de-..

or" SCANNING AND- A v l. "-.;THEREFOR e gs-4. m Nwyar; fi n Application name; 9, 1930, Serial No.:501,026

J r ii scribed, delineated m the accompanying draw ings, and particularly pointed out in thatpor-J tion of this instrument wherein patentable'novelty is claimed fcnc'ertain and peculiar features of the invention, it being-understood that, with- 5;

in the scope of what hereinafter thus is claimed, divers changes in=='the 'form, proportions,' size and minor details of th structure may be made without departing from the spirit of, or sac-' rificing 'any 'o'f the "detailsof'the invention. 10

-In de'scrib ing the invention in detail, refer ence "is' had 'to the accompanying drawing} wherein I have illustrated embodiments of my invention, and, wherein like characters of refout theseveral views, 'andin'which:- "Figure-lfisa diagrammatic view of one" em-" bodiment of the' -invention for scanning motion picture film,"and Fig. 2 is 'also a diagrammatic erence, designate corresponding parts through- 15 1 vie'w of a modified'embodiment thereof, and20.

Fig; 3 is a plan "view of a motion picture film illustrating the results of a'- known method of' scanning motion picturetfilm. :I. Fig. 1 is a diagrammatic view of one embodiment of the invention for scanning motion pic 2 ture film and in which the film I having motionpicture frames 2 is arranged to be continuously advanced by sprockets or rollers. 3--3 relatively to aperture; plate or member 4 having aperture,

5 arranged transversely of said motion picture 30 1 frames whereby the motion pictures thereon maybe scanned from one side to the other thereof through said aperturer. a; -;Optical.systen1 I0 isarra ged a to project a light beam Xi of light rays projected from 35 lightv source ontoI vibrating mirror or reflecting memberl'l 2 a. pivotally' supported by shaft l3, the armature .M securedto said mirror being arranged to reciprocate under the influence of alternating current flux generated yoke 15 by magnet coils lG-IS. g A

A similar optical system 20 is arranged to project "a light beam Yl of the light rays pr'o jected from light source 2| onto vibrating mirmm or reflecting member 22 pivotally supported byshaft 23, the armature 24 secured to said mirror being arranged to be reciprocated by the influence of alternating current flux generated iii magnet yoke 25'by the magnet coils 26-26,

in magnet v 40 th ecoils l6 and '26 being 'supplied'by high frequency 'alternating current from alternating currentgene'rator.30. 5r; wa n-5:1

1': Also energized; by? generator .30 are synchronous. motors IJ andZ'Larranged-to rotate shut-.2

ters l B andv 2 8 havingopaque portions {8a. and;

28a. and transparent portions [8b and 2% arranged to intercept the secondary light beams X2 and Y2 during each revolution thereof.

The light sensitive cells l9 and 29 are arranged in multiple in an energized circuit 31 including an amplifying unit 32 associated with the television broadcasting station 33 arranged to broadcast televised motion pictures over aerial 34.. u The operation of applicants system is as followsz-the armatures I4 and 24 vibrate Synchronously with the rotation of synchronous motors I 7 and 21, in other words, the reciprocating armatures l4 and 24 complete aficycle of two movements during each revolution of said motors I1 and 21. During the movement of armature l4 and mirror l2 supported'thereby' to project light beam XZ'from the left side of aperture 5 to the right side thereof, the transparent portion iBb of shutter l8 registers with said beamwhereby the motion picture frame 2- maybe scanned from left to right and during the movement of said armature and mirror to project light beam X2 from the right to the left side of-aperture 5, the opaque portion law of shutter l8 registers with said projected beam thereby. cutting off said light beam and preventing the projection thereof onto said aperture.

nous motor-21 in' projecting and intercepting the light beam Y2; is similar to that described in connection with armature l4 and motor i1 namely, that as mirror 22 acts to project light manner tending to produce a continuous move-:

ment of the beams alternately over said aperture, one of the beams beginning to' moveto the right from the left sideof said aperture simultaneously with the'other beam moving tothe left from the right side of said aperture, the movement of the both beams to 3 the left however being intercepted by the opaque por-' tions of the shutters whereby only' movement thereof to the right is projected onto said aperture in this manner producing unidirectional scanning of themotion picture frames 2.

. The width of aperture 5 longitudinally of the film ispreferably such that, as one light beam" completes its scanning at the right marginof;

the frames, the portion of the frame previously scanned at the lefthas just passed or registers withthe upper edge of said aperture, in. this manner effecting substantially a complete scan-. ning of the area within said frames as saidfilm is advanced. s

in a paper .before the Society of Motion Picture Engineers spring'meeting held at Washington;

D. C. May 5th, "to'8th; inclusive, 1930, orsaid apparatus may be of any other form wherein'the" 11110121011 pictures'to be broadcast are scanned by a beam of light as the film depicting said motion pictures is advanced.

Referring to Fig. 2, light source 4| associated with beam splitting device 42 is arranged to form light beams X3 and X4 directed onto reciprocating member 41 supporting angularly disposed mirrors 43 and 44, the reciprocated portion of beam X4 being reversed in direction of movement by reflecting member .45 whereby the beams X3 and X4 as projected onto film I are moved oppositely thereacross. Whereas the shutters l8 and 28 are shown as cancelling the scanning effect of the beams during the movement in one direction'thereof across the film, a single shutter as 43 arranged to alternately cancel the movementof said beams may be employed. Should any variation in the light intensity of the source H v also representing successiveapertures in the The operation of 'armature 24 and synchro scanning disk, said apertures, due to their comparatively smallopening and peculiar location relatively on'said' disk, being extremely difiicult to accurately form as well as accurately allocatef. As aniexample of common errors .in forming said apertures, the apertures A are too long longi-. tudinally of the film, therefore overlap and cause super-imposition of light during scanning thereof and therefore distortion as differing areas of the motion pictures have been scanned 'by each light spot'A-+A-A. The aperture B is too narrow, or improperly located with respect to A and (Jv .and therefore produces an unscanned line between A and B rows producing further distortion. .If B is of :the correct width .but mallocated a superimposed area will be formed between the rows B and C, producingstill further distortion. Both too narrow aperture and/or- 'mal-location may be caused by a difference of hardness in the metal of the disk on each side of the aperture, the punch making saidaperture being strained sidewise therebyalso causing shearing and deforming of said aperture as mentioned, The aperture C is assumed to 'be smalleri than the correctsize due to being formed exclu sively in a hard spot of said disk thereby causing unscanned areasv both longitudinally and transversely of the film thereby causing still further distortion of the televised pictures. To overcome the aforesaid dark line distortion caused by unscanned linear areas some disks are employed wherein the apertures are made slight-- 1y larger than 'the theoretical size whereby adouble scanned area is formed around each scanned spot as A-D, and whereas the distortion due to dark lines is omitted, the distor-" tion due to double scanning is proportionately 1 1 f increasedJIn th l J The broadcasting apparatus of the station 33, e app wants method of scan with the exceptionof the scanningdevice, may be of that form described by Dr. V; Zworykin,

the scanning Y light are 'absent thereon. fivii 75 -:Whereas'iamaslcing member, as I Ihas been shown as placedadjacentthe film "I, it is to-be understoodthat said member-may be omitted and a masking member as shownin the applicants copending application Serial No. 501,025, filed, December-"9th, 1930, may be interposed in the converging portion of light beam XI and Yl. -;This application dorms impart a continuing application ofmy 'copending application, Serial No. 501,025, filedDec'; 9,1930. 1: -'.'i 2v L v Whereas two light sensitive cells [9 and 29 have been'showmionly one cell may be employed being. so disposed and proportioned whereby both the light-beams X2 -and:.Y2 willbe projected through the .feye? thereofas film [is advanced. liWhat I claim is:-"..'. n} n l 7--1; '2 1; :The method of unidirectionally scanning motion pictures recorded onto motion picturefilm advancedrelatively to alight sensitive cell associated with 'rtelevision broadcasting apparatus: which optically projecting two beams of light through thefm'otion pictures onto the light sensitive cell', and during the projection reciprocating the beams from one-margin of the picturesto the' other'ifor' the scanning thereof, the'lightiheams traveling 'in opposite direction'during movement from one mar-' ginto the other, and-: din'ingmthereciprocal movement of the beams annulling the scanning effect thereof 'during the movement in one direction thereof withouixamnilling' the scanning effect when. moving in the opposite direction between the margins whereby the pictures will be unidirectionally scanned without interruption as the film is advanced.

2. Television scanning apparatus for scanning motion picture film, the film being arranged to be advanced relatively to a light sensitive cell associated with television broadcasting apparatus comprising, means for optically projecting a beam of light arranged to pass through the advancing film onto the light sensitive cell for scanning the motion pictures thereon, means for projecting a second beam of light arranged to pass through the advancing film onto the light sensitive cell for also scanning the motion pictures thereon, means positioned in the path of the beams for effecting a reciprocal movement thereof between the margins of the pictures on the film, one of the beams moving oppositely to the other during the reciprocal movement across the pictures, and means positioned in the path of the reciprocating beams arranged to annul the scanning effects thereof when traveling in one direction but not so cancel the scanning effect when traveling in the opposite direction whereby the film is unidirectionally scanned by both films continuously as the film is advanced.

3. Television scanning apparatus comprising, means for advancing a motion picture fihn having motion pictures recorded thereon, the film being advanced at a uniform rate of travel, a light sensitive cell included in a television broadcasting circuit positioned relatively to the advancing film, means for optically projecting a plurality of light beams, light directing means positioned in the path of the beams arranged to re-direct the light rays thereof through the film onto the light sensitive cell for producing a modulated beam as projected thereonto, means affecting the light directing means for effecting a, reciprocation of the beams from one edge of the motion pictures to the other for the scanning thereof as the film is advanced, certain light T'beams, fbeing *re'ciprocated oppositely Tto other lightbeamsyiand means positioned in the path of the reciprocating beams arranged to intercept the light rays thereof during: the portion of the reciprocating cycle-the beams move in'one direction across the picturesand not'so intercept-the beams during the portion of the cycle the beams move in the opposite direction whereby the pictures are unidirectionally and uninterruptedly scanned as the film is advanced.

4. In apparatus for scanning motion picture film having alight sensitive cell rearwardly thereof, means for advancing the film continuously at a uniform rate of travel, a light source, means for optically forming the light source into a scanning spot, a device including a light deflector for reciprocating the scanning spot transversely of the film with respect to the advancement thereof, a pulse motor for operating the device, a shutter arranged to periodically intercept the scanning spot during one portion of the reciprocation thereof by the reciprocating means, another pulse-motor for operating the shutter, asource of pulsating energy connected to both of the motors, the fiow of energy from the source to the motors effecting interception of the scanning spot by the shutter when the reciprocating means is reciprocated in one direction but not intercepted thereby when the reciprocating "means is 'reciprocated in the opposite direction whereby the film is unidirectionally scanned. incur. r

5. In apparatus for scanning motion picture film having a light sensitive cell rearwardly thereof, means for advancing the film at a uniform rate of travel, means for projecting a plurality of independent light beams having scanning spots arranged to impinge on the forward side of the film for directing modulated light therethrough onto the cell, means correlated to each light beam for optically reciprocating the scanning spots transversely of the film with respect to the advancement thereof, means synchronously operating the scanning spot reciprocating means for reciprocating the spots in relatively opposite directions of travel, and shuttering means for cancelling the scanning spots at the film during the reciprocation thereof in one direction and not cancelling the spots during the reciprocation thereof in the other direction whereby the film is unidirectionally scanned during the advancement thereof.

6. In apparatus for scanning motion picture film having a light sensitive cell rearwardly thereof, means for advancing the film at a uniform rate of travel, means for projecting a plurality of independent light beams having scanning spots arranged to impinge on the forward side of the film for directing modulated light therethrough onto the cell, means correlated to each light beam for optically reciprocating the scanning spots transversely of the film with respect to the advancement thereof, means synchronously operating the scanning spot reciprocating means for reciprocating the spots in relatively opposite directions of travel, shuttering means for cancelling the scanning spots at the film during the reciprocation thereof in one direction and not cancelling the spots during the reciprocation thereof in the other direction whereby the film is unidirectionally scanned, a mask member positioned forwardly of the film, and a light slit therein parallel to the path of travel of the scanning spots, the slit having a width less than the width of the scanning spots.

"ZuApparatus for scanning objects comprising, means for optically forming two beams of light. each having a scanning spot portion, means for: reciprocatingthe a scanning spot .portions over. the object for the scanning thereof, the scan-- ning spotportion being'reciprocated in parallel planes at the point of,-contact with the object, one of the beams moving oppositelyto the other beam during the reciprocation thereof, means for moving the beams and the object relatively; the planeof movement being disposed angular- 1y 'withrespect to'the plane of reciprocation of the beams;.andmeansaffecting the beamsv a12- ranged to cancel the scanning effect of-the scanning spot portion during the movement thereof;

only in one. direction whereby the object will becontinuously unidirectionally scanned. l

-18. In apparatus for-scanning an object; meansfor projecting a plurality of continuously illumi nated. beams of light havingscanningspots im-; pinging on the object, means correlated to each: for optically. reciprocating the scanning .spots over the object in relativelyopposite directions or travel; shuttering means correlated to eachlight beam forcancelling thespots :duringone direce tion of travel thereof and not cancellingthe spots during the opposite direction of ,travel thereof, and means synchronously operating the optical reciprocating means and the shuttering means for effecting successive unidirectional, travel of the scanning spots over the object; -r=

9. In apparatus for scanning an object, means wt-maul. "n,

fora projecting a plurality of continuously illuminated light bea'ms-having-scanning spots im'- pinging on the .object, means correlated to each. light beam for optically reciprocating the scam; ning spots 'over the object in relatively opposite planes of travel, shuttering means correlated to each light beamfor cancelling the spots during one direction of travel thereof and not cancelling the spots during the opposite direction of: travel thereof, means'synchronously operating the optical reciprocating means and the shuttering means for efiecting successive unidirectionalv travel of the scanning spots over the film, a mask member: positioned in the path of the "light beams, and a light slit therein parallel to the: plane of travel of the scanning, spots," thev slit having. a width less than the width fhe scanningspots. "x5; irixia: f:'; .l.. 71.11:) 1?-10.In the art of television the method of scanning an object which involvesmptically projecting a plurality of-continuously illuminated beams .of

light, :each-beam having a scanning spot of similarjarea arranged to scan the object, optically reciprocating the light. beams in opposite directions for reciprocating the"scanning spots over the object, duringthe scanning'operation alternately intercepting each light beam for produc-"- ing unidirectional scanning of the object, and during .the scanning operation also. moving thev object inra plane disposedangularly to the of movement of the scanning spots. .m.

- i) n n :OSCAR A. ROSS.

- '4 I it r 5 mins erit' in 1 n ail-i as icereci gninnsoa plane 

